The plates of parallel plate capacitor of capacity $100 \mu F$ are charged to potential $100 v$and then seperated from each other so that distance between them is doubled. How much energy is spent in doing so ?

Question

$(A)\;0.5 \;J \\ (B)\;0.25 \;J \\ (C)\; 2.5 \;J \\ (D)\;5\;J$